MerCruiser Thermostat Cover Housing – 8M0061068 (454 / 502 Big Block)
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
The Mercury / Quicksilver 8M0061068 Thermostat Cover Housing is a genuine OEM upper thermostat housing cover used on MerCruiser GM-based marine engines.
This component sits on top of the thermostat housing and seals the thermostat assembly, directing coolant flow into and out of the engine. It is a structural and sealing component, not a thermostat itself, and is critical for maintaining proper coolant circulation and system pressure.
The housing features an offset (diagonal) bolt pattern and is designed to work with big-block MerCruiser cooling systems. It replaces earlier designs while maintaining OEM fit and flow characteristics.
Key Features
- Genuine Mercury / Quicksilver OEM part
- Thermostat housing upper cover / cap
- Maintains proper coolant flow and sealing
- Designed for high-flow big block cooling systems
- Corrosion-resistant marine construction
- Direct OEM replacement
Engine Compatibility
MerCruiser GM-Based Engines
Commonly used on:
- 454 CID (7.4L) V8
- 502 CID (8.2L) V8
- High-performance big block engines
Typical Applications
- MCM (sterndrive)
- MIE (inboard)
- TRS and Bravo systems
➡️ Found on engines such as:
- 330 / 340 / 370 / 400 / 420 / 425 / 440 models
- 454 MAG Alpha
- 7.4L and 8.2L big block platforms (1980s–1990s era)
Serial Number Fitment Notice
Fitment depends on:
- Engine displacement (454 / 502)
- Cooling system configuration
- Housing bolt pattern
⚠️ Always confirm compatibility using your engine serial number before ordering.
Specifications
- Part Number: 8M0061068
- Type: Thermostat housing cover
- Function: Seals thermostat housing and directs coolant flow
- Bolt Pattern: Offset / diagonal
- Material: Marine-grade cast metal
- Weight: ~1.5 lbs
What’s Included
- Thermostat housing cover only
(Gasket and thermostat sold separately)
When This Part Needs Replacement
- Coolant leak at thermostat housing
- Corrosion or pitting on sealing surface
- Warped or cracked housing
- Stripped or damaged bolt holes
- During full cooling system rebuild
Installation Notes
- Always replace gasket when installing
- Clean mating surfaces completely
- Check thermostat housing base for corrosion
- Torque bolts evenly to avoid warping
- Pressure test cooling system after install
Alternate / Superseded Part Numbers
OEM Cross References
- Mercury / Quicksilver: 8M0061068
- Supersedes: 47442A1 / 47442
Shipping
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
💡 Parts Desk Insight
If you’re replacing this cover, inspect the lower housing too—on big blocks, corrosion usually affects both surfaces, not just the cap 👍
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.